There are very many types of valves to control the flow of fluids in their many states. These include everything from basic plumbing valves or faucets to two-way or multiple-function valves. More sophisticated valves, such as seen in the U.S. Pat. No. 4,195,631, to Baucom for a "FLOW REGULATING DEVICE USEABLE IN PLASMA PHERESIS" can switch between two or more sources or outlets for special purposes.
Multiple switching, such as this, is necessary where fluid inputs or outputs, from or to a plurality of reservoirs, must be directed to a common input or outlet, or be reversed, in direction of flow after processing, as in dialysis or plasma pheresis. In some of these functions, the flow must be laminar to avoid vortices and possible formation of bubbles that could create embolism, for example. This would preclude the use of many types of valves or petcocks, well known and commonly available for medical and other purposes.
Multiple input or output valves could involve separate cntrols or a single, rotary switching mechanism, as in Baucom. However, while the concept is simple and basic, its function and switching procedures become complex. The simple movement of an opening or port along a series of other openings to alternately open and close the openings in sequence, either in a linear path or in a circular path, is an obvious solution, but is over-simplified in theory and does not necessarily work in practice.
Either the surfaces must be in close contact, with considerable friction between the elements as the openings are moved from one alignment to another, or they must be clamped, when they come into alignment, to insure a seal against leakage. This is the case in Baucom, where the mechanism must be tightened by screw threads when it is in position, and then loosened, with inevitable leakage, to move on to the next position.
Another serious problem with the more sophisticated switch valves is cost. Devices such as that of Baucom are expensive to manufacture, and must be cleaned and sterilized after each use, since they could hardly be considered disposable.
It is therefore an object of this invention to provide a simple, rotary valve that turns easily from one source to another, providing laminar fluid flow and almost no leakage. It is a further object of this invention to provide a multi-function valve that has few moving parts. It is a further object of this invention to provide a valve that has moldable parts for low cost and easy assembly. It is a further object of this invention to provide a multi-function valve, particularly useful for medical purposes, that is disposable.